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Re: sequential numbering across more instances
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Re: sequential numbering across more instances


  • Subject: Re: sequential numbering across more instances
  • From: Ondřej Čada <email@hidden>
  • Date: Fri, 15 Aug 2008 17:03:18 +0200

Florijan,

On Aug 15, 2008, at 4:23 PM, Florijan Stamenkovic wrote:

I've just bumped into a need to maintain a sequential numbering of database rows, which are created by more concurrent WO application instances.

If you just need a unique identifier for a row, you could use the primary key value easily,

I regret to say I have a very strong feeling against using PK's for anything but PK and relationships, ever.


so I am guessing that is not what you need. So, could you elaborate on this a bit?

Anyway, even if I wanted to use them, it would not do, for there are items which have no numbers... Ha, thanks! Seems you just have led me to one reason I haven't realised originally why UNIQUE would not work quite well :) (Unless put into a table of its own, dedicated for this task, which I at the moment have alas completely no idea whether it's worth that or not... I think rather not?)


What kind of a sequence is it? Do the users need to provide values, or can they be auto generated? In short, what are you trying to do?

There's an entity, say, Order, one of whose attributes is an integer orderNumber.


Some of created orders have no number (test ones, etc.). Those which have a number need to be numbered in a global sequence. In pseudo- code, I need a method

class Order:EOGenericRecord { ... ... ...

void assignOrderNumber() {
// precondition: orderNumber()==null
...
...
// postcondition: orderNumber() is unique, so that all numbered orders make a sequence 1,2,3,4,....
}


so that this method works properly from any number of application instances.

Thanks!
---
Ondra Čada
OCSoftware:     email@hidden               http://www.ocs.cz
private         email@hidden             http://www.ocs.cz/oc



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  • Follow-Ups:
    • Re: sequential numbering across more instances
      • From: Chuck Hill <email@hidden>
    • Re: sequential numbering across more instances
      • From: Mike Schrag <email@hidden>
    • Re: sequential numbering across more instances
      • From: Florijan Stamenkovic <email@hidden>
References: 
 >sequential numbering across more instances (From: Ondřej Čada <email@hidden>)
 >Re: sequential numbering across more instances (From: Florijan Stamenkovic <email@hidden>)

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